A Time Division Multiplex System for Telemetering Purpose

A basic design using time division multiplexing principles is reported for telemetering some measurements in a remote water-pumping station. A total number of twelve channels is provided and the bandwidth per channel is 300 Hz working from dc upwards. The discussion is emphasized on simple but adequate design techniques using inexpensive components. For the sake of clarity, only unconventional circuits used for multiplexing and de-multiplexing are described in detail, other more well-known building blocks being referred to the literature. The system has undergone extensive tests in the laboratory and its general performance is satisfactory and not affected by considerable fluctuation in sampling rate or power supply voltage. The de-multiplexing receiver also has the special characteristic that it can be made to scan continuously over every time-slot to select any channel in the system as desired, providing a time-domain equivalent to continuous tuning in the frequency-domain, a property particularly useful for testing TDM sources.